1. Field of the Invention
The present invention relates to methods for bonding members to each other. In addition, the present invention relates to methods for manufacturing airtight containers and image display devices.
2. Description of the Related Art
Airtight containers have been widely used. In particular, in the field of image display devices, manufacturing of airtight containers has been a very important technique.
At present, for image display devices, a cathode ray tube (CRT) has been widely used. In recent years, a CRT tube having a display screen size of more than 30 inches has been introduced on the market.
In addition, as a flat type image display device, for example, there may be mentioned a plasma display device (PDP) in which a fluorescent film is excited to emit light when irradiated with ultraviolet rays, and a flat type image display device in which a fluorescent film is excited to emit light when irradiated with electrons emitted from an electron emission element such as a field emission type (FE) electron emission element or a surface conduction electron emission element used as an electron source. Recently, a PDP having a large screen size, such as approximately 40 inches, has been available on the market.
Since the image display devices as described above each have an airtight container, the manufacturing method thereof comprises a step of forming an airtight container. For example, a manufacturing method of an image display device has been known in which a substrate for an electron source and a substrate provided with a fluorescent film are bonded to each other to form an airtight container.
A method for bonding two members to each other, a method for manufacturing a vacuum envelope using the bonded two members, and a method for manufacturing an image display device using the above envelope are disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2002-184313. In this patent document, the structure is disclosed in which a metal sealing material is supplied on an underlayer, and sealing is then performed.
In addition, in Japanese Patent Laid-Open No. 2002-182585, the structure is disclosed in which indium and a silicone adhesive are disposed side by side on a frame, and sealing is then performed.
FIG. 13 is a schematic view of a general structure of a display panel formed of an electron source substrate and a large number of electron emission elements disposed thereon. In addition, FIG. 21 shows a schematic cross-sectional structure of a peripheral portion of a display panel (envelope 90).
In FIGS. 13 and 21, reference numeral 81 indicates an electron source substrate on which a large number of electron emission elements (not shown) are disposed, and this electron source substrate 81 may be called a rear plate in some cases. Reference numeral 82 indicates a face plate in which a fluorescent film, a metal back, and the like are formed on a glass substrate. Reference numeral 86 indicates a support frame.
The envelope 90 is formed by adhering the rear plate 81, the support frame 86, and the face plate 82 to each other for sealing. Hereinafter, a process of sealing the envelope will be briefly described with reference to FIG. 21.
First, the rear plate 81 and the support frame 86 are bonded to each other beforehand with a frit glass 202.
Next, an indium (In) film 93 used as a panel boding agent is provided for the support frame 86 and the face plate 82 by soldering. In this step, in order to increase the adhesion of the In film 93 to the support frame 86 and the face plate 82, silver paste films 204 are provided as an underlayer as shown in FIG. 21.
Subsequently, in a vacuum chamber, sealing is performed by bonding the support frame 86 to the face plate 82 with the In film 93 provided therebetween at a temperature equal to or more than a melting point of In, thereby forming the envelope 90.